I was doing a timed run tonight with my phone, and while I was doing it I noticed my car was hesitating around 5800 rpm. I noticed this before (after I got GMS1 installed<- might have answered my own question) but it doesn't seem like every time. I mostly notice it in 3rd and 4th. Any ideas as to why this is happening? It also sometimes seems like it surges once in awhile in traffic. Boost flutters a little but doesn't appear to cut out. Planning on phoning my dealer tomorrow. No CEL comes on. I have also missed a couple NLS's. I think that is most of the needed information.

 

Just thought of a couple more things. The dealer said they had some trouble with my car accepting the new tune. I had the car tuned on June 16 2011, at 16,220km. Car now has just over 20,000km.

 

Talk with BYT. I think he had a similar issue.

 

The LSJ's used to have a very similar issue, felt like a brief hit of the rev limiter right around 5700rpms. I forget what the reasoning was, but it's basically normal, nothing to do about it. It has something to do with the reluctor wheel on the crank or something in the PCM IIRC.

 

It doesn't always do it though, and I do not recall it ever doing it before I got the GM tune.

 

ecu cant keep up with where the engine is at? that sounds like something stupid gm would do.

 

Bro it could be a ton of things ranging from the easiest .... Spark blowout, bad plug or plugs, bad coil, bad injector, your 3 bar map sensor are not soldered correctly.and ect

 

Well the dealer told me to bring in my car next time it does it and I'll have to take a tech for a drive. If I remember correctly it does it till redline, or at least the last time it did.

 

Was the same way with mine. Not all the time, usually only in 3rd or 4th gear, didn't really do it stock but with the GM stage kit was more common.

 

Ya I don't think it does it in 2nd, but 2nd goes by way to quick. I wonder what the tech would think about me going 160+km/h just to show him the problem.

 

Technically they don't have to warranty anything that is only present during unsafe operation of the vehicle, so it might not be the best idea

 

Maybe the engine is choking with stage 1 at that high of RPM. Stock air box with 2 massive catalytic converters still on the car?

 

Yes. The only performance mod is GMS1.
I have been thinking about reving the car that high under lighter throttle, but I just don't think I could bring myself to rev that high without being in the throttle pretty good.

 

If you change out the downpipe with a high flow cat, I bet the hesitation will subside. I know the Hahn downpipe will not throw an engine code because I've had one, but can't be sure with other brands.

 

Kinda funny you would suggest that. I keep thinking and putting exhaust on the car.

 

Would Cat over temp cause this ? It kinda sounds like spark blow out .... I would check your plug gap and throw a new set of plugs in it. Do you have anything that measures knock ?

 

Why would it be the plugs already (just over 20,000km)? The only thing I have that measures knock is the rpd. Other than that no.

 

i have the hahn catted downpipe with the gms1 and have not ever thrown a code with it!

 

I bet it is from a bad GMS1 install.

 

I'll be seeing if it will do it aging after work. I hope it won't. I blew out my air filter today and basically no dust came out of it.

 

Well, couldn't check it after work today. It rained and I'm not about to risk it on wet roads.

 

Could be losing communications with the TMAP or MAP, at least by his original description. If the TMAP harness is shitting the bed boost readings end up all over the place and it can take a while to get the inevitable "5PSI max" symptom.